import java.util.Scanner;

public class l5 {
    public static void main(String[] args){
        while (true){
        Scanner reader = new Scanner(System.in);
        System.out.println("请输入正确的成绩：");
        double x = reader.nextDouble();
            if (x<0 || x>100){
                System.out.println("成绩输入有误，请重新输入");
            }
            else if (0<=x && x<=59){
                System.out.println("您的等级为C");
                break;
            }
            else if (60<=x && x<=80){
                System.out.println("您的等级为B");
                break;
            }
            else {
                System.out.println("您的等级为A");
                break;
            }
        }
    }
}
